Objective: An online, Web-based peer evaluation was designed to enable students enrolled in a basic pharmacology course to complete an anonymous peer evaluation reflecting students' contributions to a variety of small-group class activities. Description: As part of the ongoing curriculum renewal at the University of Missouri—Kansas City (UMKC) School of Medicine, small-group activities were incorporated into a historically successful lecture-based course in basic pharmacology in 2000. The class was divided into six small groups (six or seven students per group) and over a two-month period each group completed three activities: They solved six problem-based learning cases, they wrote a group paper, and they delivered a formal group presentation on an assigned topic using an evidence-based medicine approach. Small-group activities were introduced into the class to address three objectives in UMKC's competency-based curriculum: problem solving, effective communication, and lifelong learning. A peer evaluation was introduced into the course to allow each student to complete an anonymous peer evaluation for every student participating in the group. The evaluation allows students to rate the contribution of each group member to the overall success or failure of the group effort, and it addresses a concern expressed by students that all group members receive equal credit regardless of individual effort. The results of the peer evaluation were used in assigning student grades. The online evaluation was prepared using FrontPage 2000, and students were able to complete it on any computer with Internet access. The evaluation consists of 15 items, which students rate using scores of 1 to 5. To complete an evaluation, each student enters his or her social security number and selects a group member by selecting the group member's name from a drop-down box. These two pieces of information are collected to ensure that each student submits only one evaluation for each student in the group and to facilitate data analysis. Many of the items address issues of professionalism. Each student receives a summary of his or her peer evaluations within 72 hours via e-mail, and in addition to the personal scores the students receives an aggregate score for their group and for the class for each evaluation item. The online peer evaluation allows students to add anonymous written comments, which are also returned to each student within 72 hours via e-mail. Discussion: The online peer evaluation was well accepted by the students, based upon written comments on the evaluation. There was a strong correlation between the students' written comments and numerical ratings of their fellow group members. The evaluations enabled faculty to identify students who had made outstanding or marginal contributions to small-group activities; they enabled students to share their assessments with their peers anonymously. Because of this success, the process will be continued in future classes and will probably be adopted by other courses. A significant modification planned for upcoming classes is that aggregated comments and rankings for each student will be shared with the student's faculty mentor.